Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 May 1;81(1):72-77.
doi: 10.1097/QAI.0000000000001971.

Brief Report: Validation of a Urine Tenofovir Immunoassay for Adherence Monitoring to PrEP and ART and Establishing the Cutoff for a Point-of-Care Test

Monica Gandhi  1 , Peter Bacchetti, Matthew A Spinelli  1 , Hideaki Okochi  2 , Jared M Baeten  3 , Oraphan Siriprakaisil  4 , Virat Klinbuayaem  4 , Warren C Rodrigues  5 , Guohong Wang  5 , Michael Vincent  5 , Tim R Cressey  6   7   8 , Paul K Drain  3
Affiliations

Brief Report: Validation of a Urine Tenofovir Immunoassay for Adherence Monitoring to PrEP and ART and Establishing the Cutoff for a Point-of-Care Test

Monica Gandhi et al. J Acquir Immune Defic Syndr. .

Abstract

Background: Current pharmacologic adherence monitoring for antiretrovirals involves expensive, labor-intensive liquid chromatography/tandem mass spectrometry (LC-MS/MS)-based methods. Antibody-based assays can monitor and support adherence in real time. We developed a tenofovir (TFV)-based immunoassay and further validated it in a directly observed therapy (DOT) study.

Design: Pharmacologic DOT study of TFV disoproxil fumarate (TDF)/emtricitabine (FTC) administered to HIV-noninfected volunteers.

Methods: The TARGET study provided directly observed TDF 300 mg/FTC 200 mg 7 (high adherence), 4 (moderate), and 2 doses/week (low) to 30 volunteers (10/group) in Thailand, collecting a total of 637 urine samples over 6 weeks of administration and during washout. ELISA measured urine TFV levels by the immunoassay and LC-MS/MS-based concentrations served as the gold standard. A mixed-effects regression model evaluated cutoffs for a point-of-care assay. Performance characteristics of the immunoassay were compared with LC-MS/MS at a chosen cutoff.

Results: Median TFV levels were 12,000 ng/mL by the immunoassay 1 day after dosing; 5000 ng/mL 2 days after dosing; 1500 ng/mL 3 days after dosing; and below the lower limit of quantification thereafter (≥4 days). An immunoassay cutoff of 1500 ng/mL accurately classified 98% of patients who took a dose 24 hours ago as adherent. The specificity and sensitivity of the immunoassay compared with LC-MS/MS at the 1500 ng/mL cutoff were 99% and 94%; the correlation between TFV levels by the 2 assays was high (0.92, P < 0.00001).

Conclusions: We have developed a novel TFV immunoassay that is highly specific, sensitive, and correlates strongly with LC-MS/MS measurements in a large DOT study. Adherence benchmarks from this DOT study will guide the development of a low-cost rapid point-of-care test for pre-exposure prophylaxis and antiretroviral treatment adherence monitoring and interventions.

PubMed Disclaimer

Figures

Figure 1:
Figure 1:
Probability of urine TFV level by immunoassay being below different cut-offs based on hours since last witnessed dose in TARGET DOT study
Figure 2:
Figure 2:
Performance Characteristics of the Urine Immunoassay Figure 2a: 2 × 2 table of LC-MS/MS vs immunoassay TFV levels (based on cut-off of 1500ng/mL) in urine samples collected in TARGET (n=637) LC-MS/MS gold standard. TP = True positive; FP = false positive; FN= false negative; TN = true negative Figure 2b: Correlation of urine immunoassay TFV levels with LC-MS/MS levels in TARGET urine samples with drug detectable via both assays (n=274)
See this image and copyright information in PMC

References

    1. van der Straten A, Brown ER, Marrazzo JM, et al. Divergent adherence estimates with pharmacokinetic and behavioural measures in the MTN-003 (VOICE) study. J Int AIDS Soc. 2016;19(1):20642. - PMC - PubMed
    1. Kimulwo MJ, Okendo J, Aman RA, et al. Plasma nevirapine concentrations predict virological and adherence failure in Kenyan HIV-1 infected patients with extensive antiretroviral treatment exposure. PLoS One. 2017;12(2):e0172960. - PMC - PubMed
    1. Hendrix CW, Andrade A, Bumpus NN, et al. Dose Frequency Ranging Pharmacokinetic Study of Tenofovir-Emtricitabine After Directly Observed Dosing in Healthy Volunteers to Establish Adherence Benchmarks (HPTN 066). AIDS Res Hum Retroviruses. 2016;32(1):32–43. - PMC - PubMed
    1. Liu AY, Yang Q, Huang Y, et al. Strong relationship between oral dose and tenofovir hair levels in a randomized trial: hair as a potential adherence measure for pre-exposure prophylaxis (PrEP). PLoS One. 2014;9(1):e83736. - PMC - PubMed
    1. Rosen EP, Thompson CG, Bokhart MT, et al. Analysis of Antiretrovirals in Single Hair Strands for Evaluation of Drug Adherence with Infrared-Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging. Anal Chem. 2016;88(2):1336–1344. - PMC - PubMed

Publication types

MeSH terms